Pidgin is a great multi-protocol IM client. Out of the box it provides support for 15 different protocols, including most of the important ones: MSN, Yahoo, Gtalk, ICQ, and XMPP to name a few. Two glaring omissions include Facebook IM and Twitter – both of which are built-in to Digsby by default.

The Guide is an application that allows you create documents (“guides”) which inherently have a tree (which you can modify as you please) and text associated with each node of the tree. The text itself is of the rich-text variety, and the editor allows you to modify the style and formatting of the text (fonts, bold, italics etc).

The PalOOCa Project offers the first complete Open Source MOLAP-Stack for fast, flexible and intuitive Office-based Business Intelligence. It provides an extension for OpenOffice.org Calc which allows both, read and write, access to data from within the Open Source OLAP Server Palo via Calc.

Processing is an open source programming language and environment for people who want to program images, animation, and interactions. It is used by students, artists, designers, researchers, and hobbyists for learning, prototyping, and production. It is created to teach fundamentals of computer programming within a visual context and to serve as a software sketchbook and professional production tool. Processing is an alternative to proprietary software tools in the same domain.